Background: Coffee is a major dietary source of polyphenols. Previous research found that coffee had a protective effect on periodontal disease. In this study, we aimed to investigate whether coffee extract and its primary phenolic acid, chlorogenic acid, affect the growth and protease activity of a periodontopathogen Porphyromonas gingivalis (P. gingivalis). Methods: Coffee extract and chlorogenic acid were prepared by a two-fold serial dilution. The turbid metric test and plate count method were used to examine the inhibitory effects of chlorogenic acid on P. gingivalis. The time-kill assay was used to measure changes in the viability of P. gingivalis after exposure to chlorogenic acid for 0–24 h. The protease activity of P. gingivalis was analyzed using the optical density of a chromogenic substrate. Results: As a result, the minimum inhibitory concentration (MIC) of chlorogenic acid was 4 mg/mL, and the minimum bactericidal concentration was 16 mg/mL. Chlorogenic acid at concentrations above MIC resulted in a longer-lasting inhibitory effect on P. gingivalis viability and significantly reduced associated protease activity. The coffee extract showed antibacterial activity as observed by the disk diffusion test, whereas these inhibitory effects were not affected by different roast degrees of coffee. Conclusions: Collectively, our novel findings indicate that chlorogenic acid not only has antimicrobial activity but also reduced the protease activity of P. gingivalis. In addition, coffee extract inhibits the proliferation of P. gingivalis, which may partly be attributed to the effect of chlorogenic acid.

Fluoride is present naturally in water and has been used worldwide for the prevention of caries. Several studies conducted in high water fluoride or endemic fluorosis areas reported that fluoride adversely affected children’s cognitive function, but some studies had negative findings. This study aimed to assess the relationship between urinary fluoride, dental fluorosis, and intelligence among schoolchildren living in communities with non-fluoridated drinking water. This cross-sectional study was conducted on 562 children aged 6–12 years in Taichung, Taiwan. Each child’s urinary fluoride level was determined by a fluoride-ion-selective electrode, and the dental fluorosis condition was evaluated according to the criteria of Dean’s Index. The Raven’s Colored Progressive Matrices-Parallel and Standard Progressive Matrices-Parallel were used to assess children’s intelligence. The results showed that the mean (±standard deviation) urinary fluoride concentrations were 0.40 ± 0.27 mg/L (0.43 ± 0.23 mg/g creatinine) among participants. The prevalence of dental fluorosis was 23.67%. After extensive evaluation of potential confounders, dental fluorosis and urinary fluoride were not associated with intelligence quotient (IQ) scores or grades in the regression models. In conclusion, dental fluorosis and urinary fluoride levels were not significantly related to the IQ of schoolchildren living in areas with low drinking water fluoride.

Childhood dental caries and obesity are prevalent health problems. Results from previous studies of the caries–obesity relationship are conflicting. This study aimed to assess the association between anthropometric status and dental caries among schoolchildren, taking into account dietary habits, oral hygiene, and sociodemographic factors. This cross-sectional study recruited 569 children aged 6–12 years from five elementary schools in central Taiwan. Each child underwent an oral health examination and anthropometric measurements. The DMFT (decayed, missing due to caries, and filled permanent teeth) and deft (decayed, extracted, and filled primary teeth) indexes were calculated to record caries experience. A structured questionnaire was used to collect information on food intake frequency and other related factors. The World Health Organization’s reference data was applied to define weight status: obese, overweight, and normal/underweight. The results showed that the mean (±standard deviation) deft and DMFT scores were 2.3 ± 2.6 and 0.7 ± 1.2, respectively, among participating children. The prevalence of obesity and overweight was 18.1% and 18.5%, respectively. After comprehensive evaluation of potential confounders, weight status was not an independent predictor of DMFT or deft scores in the negative binomial regression models. In conclusion, weight status was not associated with caries scores in primary or permanent teeth among 6–12 year-old schoolchildren.

Intrachamber challenge with Porphyromonas gingivalis strain 381 in a mouse subcutaneous chamber model results in a local infection that progresses to exfoliation of the chambers within 15 days. This study was designed to elucidate the contribution of host reactions to tissue destruction manifested by chamber exfoliation in animals infected with P. gingivalis . Chamber fluids showed increasing levels of prostaglandin E ₂ with infection, and the levels of tumor necrosis factor (TNF) in chamber fluids peaked just before chamber exfoliation. Intraperitoneal injection of a TNF inhibitor, thalidomide (TH), reduced the number of exfoliated chambers, while indomethacin had no effect. Exogenous TNF in chambers without bacterial infection did not cause chamber exfoliation but induced neutrophil infiltration. In a dual-chamber model, two chambers were implanted in the same mouse. One chamber was infected with P. gingivalis , and 9 days later exogenous TNF was added to the other chamber. Altogether, 66.67% of uninfected chambers were exfoliated between day 11 and day 16, although no bacteria were recovered from uninfected chambers. TH treatment alleviated both infected and uninfected chamber exfoliation. In this study, tissue destruction caused by P. gingivalis 381 infection was due to the elevation of the TNF levels and not due to local bacterial activities. Our results further indicate that local infection by P. gingivalis 381, a nondisseminating strain, actually has systemic effects on the host pathological outcome.

Biomechanics play a critical role in influencing the clinical applications of all-ceramic dental restorations. The restorative biomaterials have to demonstrate mechanical durability in the oral environment because they are always exposed to a variety of oral environments. This study was designed to evaluate the effect of soaking time, notch and saliva pH values on the impact energy of three commonly used all-ceramic materials for CAD/CAM. The leucite-reinforced glass ceramic (ProCAD), lithium disilicate glass ceramic (IPS e.max CAD) and zirconia-based ceramic materials (IPS e.max ZirCAD) were used. The experimental results indicated that the impact energy of ProCAD decreased with an increase in soaking time, but not for IPS e.max CAD and IPS e.max ZirCAD. The impact energy of the zirconia system was higher than leucite-reinforced and lithium disilicate-based ceramic systems. When subjected to preformed 0.5 mm U-shape notch on the bar specimen of 3 mm thick, the impact energy of the all-ceramic restorations revealed a markedly reduction of about 80%–90%, almost irrespective of dental compositions, which indicated the effect of flaw to a great degree. No statistically significant influence (p > 0.05) of pH values (4, 7 and 9) on impact energy was found for each group. It is concluded that the no matter which all-ceramic materials were used, it was appreciably sensitive to the presence of notches. The ceramic composition and microstructure have been shown to affect mechanical durability.